The field of medical imaging has seen significant advances since the time X-rays were first used to determine anatomical abnormalities. Large amounts of image data can be generated by modern medical scanners and there remains a need for developing image processing techniques that can automate some or all of the processes to more quickly and effectively determine a presence of anatomical abnormalities in scanned medical images.
In angiographic X-ray imaging, contrast medium is used to enhance the contrast of blood-carrying structures within patient anatomy. For example, contrast medium is introduced into a patient volume (e.g., via intravenous injection) and an X-ray image of the volume is acquired while the medium is located within the volume. In the X-ray image, structures which contain the medium appear darker than they would otherwise appear.
In DSA (Digital Subtraction Angiography), a “mask image” of the patient volume is subtracted from an X-ray image acquired as described above. The mask image is acquired without the presence of the contrast medium and represents background anatomic detail. The resulting image is intended to portray only the vessel and perfuse tissue components of the patient volume which include contrast medium.
Digital medical images are constructed using raw image data obtained in an X-ray and as derived from, for example, the DSA. The digital medical images are typically either a two-dimensional (“2-D”) image made of pixel elements or a three-dimensional (“3-D”) image made of volume elements (“voxels”). Such 2-D or 3-D images are processed using medical image recognition techniques to determine the presence of anatomical structures, and as for example in a DSA, the flow of contrast agent through vessels of the patient.
With regards to the imaging of patient vessels and understanding the flow of blood through these vessels, current tools for analyzing blood flow present overall flow information for an entire image or a user-selected region. In cases where treatment of occlusions of specific vessels needs to be analysed, analysis of more than those specific vessels, being those in an entire image or selected region, can give a misleading picture of the effectiveness of treatment. Thus, there is a need for improved automated or semi-automated systems and methods for tracking and visualizing rate of blood flow through a tracked vessel.